<form [formGroup]="formModel" (ngSubmit)="onSearch()" novalidate>
  <div class="form-group" [class.has-error]="formModel.hasError('minlength', 'title')">
    <label for="productTitle">商品名称：</label>
    <input type="text" formControlName="title" id="productTitle" placeholder="商品名称" class="form-control">
    <span class="help-block" [class.hidden]="!formModel.hasError('minlength', 'title')">请至少输入三个字</span>
  </div>
  <div class="form-group" [class.has-error]="formModel.hasError('positiveNumber', 'price')" >
      <label for="productPrice">商品价格：</label>
      <input type="text" formControlName="price" id="productPrice" placeholder="商品价格" class="form-control">
      <span class="help-block" [class.hidden]="!formModel.hasError('positiveNumber', 'price')">请输入正数</span>
    </div>
    <div class="form-group">
        <label for="productCategory">商品类别：</label>
        <select id="productCategory" class="form-control" formControlName="category">
          <option value="-1">全部分类</option>
          <option *ngFor="let category of categories" [value]="category">{{category}}</option>
        </select>
    </div>
      <div class="form-group">
        <button type="submit" class="btn btn-primary btn-block">搜索</button>
      </div>
</form>
